Nonaqueous electrolyte secondary batteries such as lithium ion batteries (lithium ion secondary batteries), because they are lightweight and have a high energy density compared with existing batteries, have been used in recent years as so-called portable power sources for personal computers, handheld devices and the like, and as power sources for propelling vehicles. In particular, lithium ion batteries, which are lightweight and capable of achieving a high energy density, are favored for use as a high-output power source for propelling vehicles such as electric vehicles (EV), hybrid vehicles (HV) and plug-in hybrid vehicles (PHV).
This type of nonaqueous electrolyte secondary battery is constructed by housing an electrode assembly having a positive electrode and a negative electrode with a separator therebetween, together with a nonaqueous electrolyte, in a battery case. In particular, nonaqueous electrolyte secondary batteries which are used as, for example, power sources for propelling vehicles, in order to stably supply a large current, have a wound electrode assembly in which are wound a strip-shaped positive electrode and negative electrode.